This invention relates generally to the control of production fluid flow from and within wells; more specifically, it concerns apparatus and method for controlling such flow within a well head and to the exterior of same.
There is need for apparatus capable of controlling flow of well fluid within a well head in such manner that control pressure transmitted to the head effects the desired control of production fluid flow, the control apparatus also being capable of ready downward installation into the head and upward withdrawal therefrom. More specifically, there is need for apparatus of this character which will selectively control flow in either or both tubing and the annulus about the tubing. Further, the apparatus should be compatable with installation of tubing into the well and withdrawal therefrom, as well as installation of sucker rod. Another advantage of such apparatus lies in the maintenance of the well in sealed condition to prevent escape of corrosive gases such as hydrogen sulfide, during well operation and during repair of the stuffing box that cooperates with the polish rod in the rod string. No prior apparatus of which we are aware meets these needs in the unusually advantageous manner as now afforded by the apparatus and methods described below.